OMG USADA Lance etc

[OakLeaf]

Riders like Merckx competed on bikes that only had 6 cogs in the cassette, the biggest being 21 (reserved for mountain stages).

Aw heck, riders like ME competed with six-speed freewheels and 42-tooth small rings and only put the 13-21 on for the super hilly roadraces. That's what there was back then. And the advice I got from my training partners in Greg LeMond's era was that a cadence of 92-96 was the most efficient.

Seriously, I've wondered what gearing the pros run for the mountain stages, but I'd be surprised if it's anything smaller than 39x21. Eleven-speed cassettes just give you closer gear ratios (just like transmissions in any other vehicle). No doubt they have 11-21 corncobs nowadays.